Ranaviruses are globally distributed pathogens in amphibian, fish, and reptile communities that appear to be emerging. Cases of ranavirus infection or disease have been confirmed in at least 177 amphibian species (25 families), 49 fish species (25 families), and 37 reptile species (17 families). Transmission of individual strains between animal classes has been documented. While ranaviruses are frequently associated with mass die-offs, host susceptibility differs among species, with some species harboring subclinical infections and likely serving as reservoirs for the virus, and other highly susceptible species amplifying the virus. Currently, there are seven recognized species of ranavirus, with stark differences in pathogenicity between strains and hosts. Several strains among these species have been named, and changes in taxonomy in this genus can lead to some confusion. Frog virus 3 is the best studied species of the genus Ranavirus, and appears to be the most globally distributed species, with viruses of this species infecting ectothermic vertebrates across three vertebrate classes. International commerce involving infected ectothermic vertebrates undoubtedly has contributed to the global distribution, diversity, and emergence of ranaviruses. This presentation will provide an overview of ranaviruses, their hosts, and their global distribution based on the author’s chapter of the same name in the coming book “Ranaviruses: Lethal Pathogens of Ectothermic Vertebrates, 2nd Edition” (Gray and Chinchar, 2024).